<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
           .box{
            width: 100vw;
            height: 100vh;
            display: flex;
            align-items: center;
            align-items: flex-start;
           
        }
        .b{
            width: 200px;
            height: 200px;
            background-color: pink;
        }
    </style>
</head>
<body>
    <div class="box">
        <div class="b"></div>
        
     </div>
</body>
</html>